Safety device for machine parts subject to high pressures



Feb. 15, 1938. A. M. ERICHSEN 2,

SAFETY DEVICE FOR MACHINE PARTS SUBJECT TO HIGH PRESSURES Filed Jan. 27, 1937 2 Sheets-Sheet 1 11M 4 W i i i 22/////// g n W1 VIII/K f Feb. 15, 1938. ERICHSEN 2,108,746

SAFETY DEVICE FOR MACHINE PARTS SUBJECT TO HIGH PRESSURES Filed Jan. 27, 1937 2 Sheets-Sheet 2 g 3 I W Q .l 2 E \H //7 Mental:

GXMLW mm MM Patented Feb. is, 1938 SAFETY DEVICE FOR moms rAa'rs suamo'r T0 men rnassuaas Abraham Martinius Erichsen, Teltow, near Berlin, Germany Application January 27. 1931, Serial No. 122,532 In Germany March 24, 1934 -9 Claims.

The invention relates to safety devices for the relief or adjustment or reduction of the pressure on machines and machine parts of every kind working with high pressures, such as rolling mills, presses and the like, in which the pressure medium of an hydraulic apparatus acts upon a safety member which at a predetermined pressure limit permits the escape of the pressure medium.

Hitherto such apparatus has required a liquid pressure medium and has necessitated packing which, under the high pressures at which the safety device is to act, has been such as to arrest or delay the action of the safety device.

This disadvantage is overcome according to the invention by utilizing a non-liquid pressure medium, that is, one which only flows under considerable pressure. Rubber, rubber dough, plasticine, gelatine or other like elastic or plastic nonliquid masses are suitable for this purpose.

The use of such a pressure medium, which is self sealing, dispenses with the necessity for packing devices, such as hitherto employed, which under the pressures in question frequently fall. A more certain functioning of the safety device is assured at a determined pressure limit. The pressure is taken up by the mass, with the simultaneous production of a secure and reliable packing and transferred or distributed to the safety element which, on attainment of the determined pressure limit, comes into action and causes the pressure mass to flow from the pressure chamber, in which the pressure is thereby wholly or partially relieved.

When the machine jams owing to anundue increase in pressure, for instance, when a rolling mill is blocked and the billet which is being rolled jams, according to the invention, the pressure can be relieved, without further ado, by hand, by means of a hand operated device which allows some'of the mass to escape from the pressure chamber so that the pressure is reduced to the desired degree. After the pressure has somewhat relaxed in this manner, the usual starting devices for the rolls may be operated again so that the pressure is wholly relieved.

The safety and relieving means may also be combined in one device, the former operating automatically on a determined pressure being reached, and the other being regulated by hand.

The mass used as pressure medium may serve at the same time to measure the pressures occurring, some of the medium being forced out through one or more openings in the pressure chamber, or acting upon a member introduced from the outside, so that the amount of the material pressed out, or the extent of the ejection movement of the introduced body, is indicated by a gauge or the like.

In the accompanying drawings, several forms of the invention are illustrated by way of example:

Figures 1 and 2 are, respectively, a sectional elevation and a plan view of one form of the invention in which the automatic device in the form of a shearing disc and the hand regulated device are arranged separately.

Figure 3 is a side elevation, partly in section, of another form in which the automatic device and the hand regulated device are combined.

Figure 4 shows the application of the invention to a rolling mill spindle.

Figures 5 and 6 are, respectively, a sectional elevation and a plan view of a further form of the invention.

Figure '7 is a sectional elevation of a form of the invention in which two different non-liquid masses are used, one serving as ejection material and the other as packing material.

In the form of the invention shown in Figure l, i is the housing of the pressure chamber containing the pressure medium 2, which acts on the safety device under the pressure of a piston 3, on which, for example, the pressure of a rolling mill spindle 4 (Figure 4) acts. The pressure chamber in the example illustrated consists of an upper part5 and a lower duct 6, which are connected by one or more openings or ducts I. In Figures 1 and 2, one end of the duct 6 is provided with a shearing'disc 8 which is arranged between the chamber wall and a nipple 9, which is screwed into the latter and on removal permits of renewal of the disc.

According to the invention, a pressure transmitting medium consisting of a non-liquid mass 2, such as rubber, synthetic or plasticized rubber, plasticine and the like, as pressure transmitting medium, is acted upon by the pressure piston 3 in the pressure chamber and also acts as a secure and reliable packing for the piston under all pressures which occur. By means of the mass 2 of'rubber or the like, the pressure is uniformly taken up and transmitted to the safety element 8, so that the latter comes into action at the predetermined highest pressure, thus avoiding the use of the usual packings which are frequent- 1y unreliable in action, render the arrangement expensive and complicated, and often require repair. In the form of the invention illustrated in Figures 1 and 2, the whole pressure chamber is filled with rubber or the like, which acts on the safety member 8 and is capable of flowing when the determined pressure limit at which the safety member comes into operation is reached, or possiblysomewhat earlier. The pressure acting on the piston 3 is taken up uniformly by the mass 2 and spreads within the mass, so that on a rise of pressure over a certain limit the shearing disc is pressed out by the mass 2. The mass 2 which passes over into the fluid condition can now escape from the pressure chamber so that the pressure in the latter, and thereby also in the machine concerned, is relieved or reduced. If a large proportion of the mass flows out, the chamber must be filled anew which can be eflected in a short time.

The device itself, apart from the shearing member 8, which must be renewed, is not damaged or rendered unemployable' by the operation described.

Besides theshearing device described, there is provided in Figures 1 and 2, moreover, a device capable of being regulated by hand, which, for example, is provided at the other end of the duct 6 and is used when the pressure is to be freed or relieved by hand. This device consists, for example, of a screwed valve M which is mounted in a housing, II and is operated by means of "a hand wheel or key applied to the squared end l2. By opening the valve ill, the pressure on the mass 2 can be so far relieved that the main pressure is relaxed.

A pressure gauge l3, Figure 2, is provided for indicating the pressure of the pressure medium and is actuated, for example, by some of the mass 2 being ejected through an opening of the pressure chamber and acting through an intermediate member on the indicating device. Instead of this, a member may also project into the pressure chamber and be pushed by the pressure of the mass 2 outwards in order to act on the gauge I3.

In the form according to Figure 3 of the drawings, the automatic device and the hand operated device are combined.

In this form, a sleeve 35 is screwed at 36 into the wall of the chamber and contains an automatic relief valve l5 which is loaded by a spring M, the tension of which can be regulated by a plug I6 having a portion 38 screwed into the internally screw-thread part 31 of the sleeve 35.

The outer end of the part 38 is squared at 39 to receive a key 4| provided with a squared bore 40 I and with a hand wheel IT. The key 4| abuts against a cap 42 formed on the part 38 and adapted to slide over the adjacent part of the sleeve 35. It has a scale on its edge l8 to indicate the amount of displacement.

By the above means, the predetermined pressure at which the valve 5 is to operate to allow pressure medium 2 to escape can be regulated by setting the tension of the spring l4 by means of the hand wheel l1, and, if desired, immediate release of the pressure medium may be effected by rotating the hand wheel I! to relieve the tension of the spring l4. The form of apparatus shown in Figure 3 may be provided with a pressure gauge similar to that shown in Figure 2.

The mass 2 in the pressure chamber in the forms of apparatus above described may be placed under a certain adjustable initial tension by a pressure pin or plunger or the like capable of being screwed from the outside into the pressure chamber.

The shearing element 8, Figure 1, and the valves In, Figure 1, and I5, Figure 3, may also be replaced by equivalent means, for example, by a displaceable piston, slide or the like.

Instead of permitting the pressure medium to escape, which requires that it be renewed, the means, such as a regulating plunger, slide or the like, may be adapted in such a manner that by the receding of the plunger, the volume or the chamber is increased, whereby the pressure is reduced or relieved. On the other hand, by inward displacement of the regulating plunger or the like, an increase .in pressure and displacement of the pressure plunger 2, Figure 1, can be eflected and of the machine part or the like resting on it,

or of a machine part influenced by its setting.

In the form of the apparatus illustrated by Figures 5 and6, the pressure medium 2' which escapes from the pressure chamber I is automatically 'returned thereto until the plunger I regains its original position. v

In this form or the appartus, the plunger I slides on a screw 28, which limits its upward stroke. A sliding member in the form of a valve I 20 having .a stem or plunger 2| is mounted in ,a housing l9 which is provided with a gland 22. A secondary chamber such as acylinder 24 is screwed onto the housing l8 andsecures the gland 22. The secondary chamber 24 contains a pressure medium such as a plastic or resilient mass 23 and with means for regulating the initial pressure of this medium, for example, an adjustable screwed plug 25. The stem or plunger 2| enters the chamber 24.

piston loaded by a weight or spring. The pressure chamber the ducts 21 and 29 and the vessel 28 are filled initially with pressure medium. The

pressure at which the medium 2 is to open the valve 20 automatically is determined by screwing in the plug 25 to regulate the pressure of the medium 23 in the chamber 24.

When the valve 20 opens, due to an undue pressure on the plunger 3, the medium 2 escaping from the chamber l enters the duct 21 and the pressure is transmitted to that in the vessel 28, which'expands as indicated by the dotted lines 28. When' the undue pressure on the machine part is relieved, the valve 20 closes, the chamber 28 contracts and a corresponding amount of pressure medium is returned by the duct 28 past the valve 3| to the pressure chamber The plunger 3 is returned to its normal position determined by the screw 26.

Hand release of the valve 20 can be eflected at any time required by screwing back the plug 25.

The elastic pocket 28 may be replaced by a similarly acting device, for example, by a plunger which is under spring pressure, the pressure of which is so strong that the mass 2 flows back automatically into the pressure chamber until the plunger 3 takes up its original position.

A plastic mass is in general to be preferred to an elastic mass, for the pressure medium 2, since it is more diflicult to cause an elastic mass to flow. Both, however, can be used in combination, for example, .as is illustrated in Figure 7, wherein 2 indicates the plastic mass which is to flow, whilst a highly elastic mass 32, for example, highly vulcanized India rubber, is used for packing for the pressure piston 3. The mass 32 in this case only has to be compressed and can always return again into its original form. The highly elastic mass 32 may bein the form of a packing ring of any suitable shape. Preferably, a conical packing ring 33 of metal or the like may be inserted at the packing joint.

' For increasing the tightness, the pressure plunger 3 in all forms of construction may be provided at the edge of its face opposed to the pressure medium 2 with inner conically extending or inwardly bent round projections, or may be hollowed out on the underside.

I claim:

1. A safety device to be interposed between parts of a-rolling mill, press or other like machine liable to be subjected to heavy pressure and adapted to relieve the pressure when a determined maximum pressure is reached, comprising a pressure chamber having an escape orifice, a pressure medium in said chamber, a plunger in said chamber for compressing said medium under the pressure applied to the aforesaid parts of the machine to be controlled, a safetyelement normally closing said escape orifice, said safety element being subjected to the action of the pressure medium and adapted to open said orifice when the determined maximum pressure is reached, the said pressure medium being a nonfluid homogeneous whole which is capable of flowing at a pressure at least as low as said maximum pressure.

2. A safety device as specified in claim 1, wherein said pressure medium is partly composed of a non-fluid homogeneous whole capable of flowing at a pressure at least as low as said maximum pressure'and partly of a highly elastic material located adjacent t9 the circumferential edge of the face of the plunger and the side of the pressure chamber. g

-3. A safety device to be interposed between parts of a rolling mill, press or other machine liable to be subjected to heavy pressure and adapted to relieve the pressure when a determined maximum pressure is reached, comprising a pressure chamber, a pressure medium in said parts of a rolling mill, press or other machine liable tobe subjected to heavy pressure and adapted to relieve the pressure when a determined maximum pressure is reached, comprising a pressure chamber, a pressure medium in said chamber, said medium being a non-fluid homogeneous whole capable of flowing at a pressure at least as low as said maximum pressure, a plunger for compressing said medium under the pressure applied to the aforesaid parts of the machine to be controlled, a safety relief valve on said chamber subjected to the pressure of said medium, resilient means for holding said valve closed against said pressure until said maximum pressureis reached, and hand operated means for regulating said resilient means to determine the maximum pressure at which the valve is to open.

5. A safety device to be interposedbetween parts of a rolling mill, press or other machine liable to be subjected to heavy pressure and adapted to relieve the pressure when a deternot above said maximum pressure, a plunger for compressing said medium under the pressure applied to the aforesaid parts of the machine to be controlled, a safety relief valve on said pressure chamber, a secondary pressure chamber containing a non-fluid pressure medium capable of flowing at a pressure at least as low as said maximum pressure, said valve having a stem protruding in said secondary chamber and being subjected to the pressure of the medium therein, and hand operated means for regulating the pressure of the medium in said secondary chamber, an escape duct for the medium discharged by the relief valve from the main pressure chamber, an expansible receiver on said duct, a return duct from said receiver to the main pressure chamber and a check valve in said return duct.

6. A safety device to be interposed between parts of a rolling mill, press or other machine liable to be subjected to heavy pressure and adapted to relieve the pressure when a determined maximum pressure is reached, comprising a pressure chamber, a pressure medium in said chamber, said medium being a non-fluid homogeneous whole capable of flowing under pressure, a plunger for compressing said medium under the pressure applied to the aforesaid parts of the machine to be controlled, a loaded relief valve on said pressure chamber for permitting the escape of pressure medium, hand operated means for varying the load on said relief valve counteracting the pressure of the medium acting on said valve, an expansible receiver for the medium discharged by said relief valve, a return duct from said receiver to the pressure chamber and a check valve in said return duct.

7. A safety device as specified in claim I, having in the pressure chamber a pressure medium partly composed of a non-fluid homogeneous whole capable of flowing at a pressure at least as low as said maximum pressure and partly of a highly elastic material located adjacent to the circumferential edge of the face of the plunger and the side of the pressure chamber, and a metallic packing between said plunger and said elastic material.

8. A safety device as specified in claim 1 wherein said pressure medium is composed of a plastic mass.

9. A safety device to be interposed between parts of a rolling mill, press or other machine liable to be subjected to heavy pressure and adapted to relieve the pressure when a determined maximum pressure is reached, comprising a pressure chamber, a pressure medium in said chamber, said medium being a non-fluid homogeneous sure medium from the pressure chamber.

ABRAHAM MARTINIUS ERICHBEN. 

